1. Field of the Invention
The present invention relates to a substrate processing apparatus for use in a spin drying apparatus (SRD), a pencil-type scrubbing cleaning apparatus, an IPA (isopropyl alcohol) drying apparatus and the like, which are used as semiconductor wafer processing apparatuses for example.
2. Description of the Related Art
In the semiconductor manufacturing process, after processing a semiconductor wafer by various processing steps, a surface of the semiconductor wafer is cleaned by supplying a cleaning liquid onto the surface of the semiconductor wafer. In a polishing step for polishing a semiconductor wafer, a polishing liquid such as a slurry and polished debris attached to the surface of the semiconductor wafer are removed by supplying a cleaning liquid onto the surface of the polished semiconductor wafer. Then, the cleaned semiconductor wafer is rotated at a high speed to scatter droplets attached to the surface of the semiconductor wafer, thereby drying the semiconductor wafer.
FIG. 1 shows an example of a pencil-type scrubbing cleaning apparatus widely known as a substrate cleaning apparatus for cleaning a surface of the substrate such as a semiconductor wafer by supplying a cleaning liquid onto the surface of the substrate. As shown in FIG. 1, the pencil-type scrubbing cleaning apparatus 10 has a rotatable substrate stage 14 having a plurality of arms 12 (four arms in this example) extending radially outwardly in a radial direction of the substrate, a plurality of substrate chuck mechanisms 16 fixed to respective distal ends of the arms 12 for gripping a peripheral portion of the substrate W, and an upper cleaning liquid supply nozzle 18 and a lower cleaning liquid supply nozzle 20 for supplying a cleaning liquid such as a chemical solution or pure water onto a front surface and a rear surface, respectively of the substrate W which is gripped at its peripheral portion by the substrate chuck mechanisms 16.
A vertically movable and rotatable support shaft 22 is vertically provided at the side of the substrate stage 14, and a base end of an oscillation arm 24 extending horizontally is connected to an upper end of the support shaft 22. A pencil-type cleaning member 26 made of, for example, PVA sponge extends downward in a vertical direction and is attached to a free end of the oscillation arm 24.
According to the pencil-type scrubbing cleaning apparatus 10, the surface of the substrate W is scrub-cleaned by supplying a cleaning liquid from the upper cleaning liquid supply nozzle 18 onto the surface of the substrate W which is gripped at its peripheral portion and rotated at a predetermined rotational speed by the substrate chuck mechanisms 16, and simultaneously by moving the pencil-type cleaning member 26 in one direction while pressing the pencil-type cleaning member 26 at a predetermined pressing force against the surface of the substrate W. At this time, if necessary, a cleaning liquid is supplied onto the rear surface of the substrate W from the lower cleaning liquid supply nozzle 20. Then, after stopping the supply of cleaning liquid, the substrate W is rotated at a high speed to scatter droplets attached to the surface of the substrate W, thereby drying the substrate W.
FIG. 2 is a cross-sectional view of the substrate chuck mechanism 16. As shown in FIG. 2, the substrate chuck mechanism 16 has a chuck body 30 extending upward and connected at its lower end to the distal end of the arm 12. A substrate placing portion 32 for placing and holding the peripheral portion of the substrate W is attached at a predetermined position along a height direction of the chuck body 30. A guide portion 34 extending upward from the substrate placing portion 32 of the chuck body 30 has an inner circumferential surface which is inclined downward toward a radially inward direction of the substrate stage. The inner circumferential surface of the guide portion 34 serves as a guide surface 36 having a predetermined inclined angle for guiding the outer circumferential end surface of the substrate W and positioning the substrate W when the substrate W is placed on the substrate placing portion 32. The inclined angle is 60±5°.
On the chuck body 30, a chuck claw 40 is rotatably supported via a support shaft 42 to hold the peripheral portion of the substrate W between the substrate placing portion 32 and the chuck claw 40 by turning the chuck claw 40 inward in a closing direction. A lower portion of the chuck claw 40 is connected via a coupling pin 46 to an upper end of a vertically movable columnar opening pin 48. The opening pin 48 is urged downward under a resilient force of a helical spring 50.
With this configuration, the opening pin 48 is moved downward under the resilient force of the helical spring 50 to turn the chuck claw 40 inward in a closing direction, thereby gripping the peripheral portion of the substrate W between the substrate placing portion 32 and the chuck claw 40. Further, the opening pin 48 is lifted against the resilient force of the helical spring 50 to turn the chuck claw 40 outward in an opening direction, thereby releasing the gripping of the peripheral portion of the substrate W between the substrate placing portion 32 and the chuck claw 40.
In this kind of pencil-type scrubbing cleaning apparatus 10, in consideration of safety or the like of transferring of the substrate W, when processing (cleaning) the substrate W having a diameter of 300 mm for example, the substrate chuck mechanisms 16 configured to define an opening (scoop opening) which is defined by connecting upper ends of the guide surfaces 36 of the guide portions 34 in a circular arc shape and has an inner diameter D1 of approximately 308.559 mm, are generally used. In this case, the height H1 of the guide portion 34 from an upper surface of the substrate placing portion 32 is approximately 8.5 mm.
Specifically, the substrate W is held generally by a robot hand, and transferred above the substrate stage 14. At this time, each of the substrate chuck mechanisms 16 stands by with the chuck claw 40 kept open outwardly. Then, by lowering the robot hand, the substrate is transferred from the robot hand to the pencil-type scrubbing cleaning apparatus 10. In consideration of deviation (backlash) of the substrate in the robot hand, teaching error by an operator, and the like, the inner diameter D1 of the opening is set to be larger than the diameter of the substrate W so as to accept the substrate W reliably within the opening (scoop opening) defined by connecting the upper ends of the guide surfaces 36 in a circular arc shape. Further, the inclined angles of the guide surfaces 36 are determined to allow the substrate W to be placed in a predetermined position by its own weight by guiding the substrate W with the guide surfaces (inner circumferential surfaces) 36 of the guide portions 34 as the robot hand is lowered. Therefore, the inclined angles of the guide surfaces 36 need to be steep to some extent, and further, as described above, the inner diameter D1 of the opening needs to be large to some extent, resulting in increasing height of the guide portions 34 from the upper surfaces of the substrate placing portions 32.
When the substrate chuck mechanism 16 having the guide portion 34 enlarged in its size is used, the amount of the cleaning liquid (water) scattered when the substrate W is gripped and rotated by the substrate chuck mechanisms 16 is increased, and a large airflow occurs. Therefore, the scattered cleaning liquid is highly likely to return to the surface of the substrate to re-contaminate the substrate or to contaminate the entirety of the cleaning apparatus. Especially, this tendency becomes pronounced when a rotational speed of the substrate is increased in order to enhance a throughput.
In order to minimize the airflow or the amount of scattered cleaning liquid (water) when the substrate W is gripped and rotated, as shown in FIG. 3, a substrate chuck mechanism 16a having a guide portion 34a which is smaller than that of the substrate chuck mechanism 16 shown in FIG. 2 and has an inner circumferential surface serving as a guide surface 36a has been used. An inner diameter D2 of the opening (scoop opening) defined by connecting upper ends of the guide surfaces 36a of the guide portions 34a in the substrate chuck mechanisms 16a in a circular arc shape is 303.2 mm (302.823 mm at the minimum value) for example, and the height H2 of the guide portion 34a from an upper surface of the substrate placing portion 32 is approximately 2.5 mm.
However, when the inner diameter D2 of the opening defined by connecting the upper ends of the guide surfaces 36a of the guide portions 34a in a circular arc shape is made smaller, the guiding function of the guide portions 34a with respect to the substrate W is weakened to make teaching tolerance for substrate transfer much smaller in order to accept the substrate W reliably within the opening having the inner diameter D2.
Further, as shown in FIG. 1, for example, when the substrate chuck mechanisms 16 are fixed to the distal ends of the four arms 12, an interval between mutually adjacent substrate chuck mechanisms 16 becomes wide, and thus the pressing force of the pencil-type cleaning member 26 against the substrate W may possibly cause the deformation or breakage of the substrate W. This tendency becomes pronounced with a higher rotational speed of the substrate W, causing an adverse effect when the rotational speed of the substrate is increased in order to enhance a throughput. Therefore, the countermeasure is demanded. Further, the substrate itself becomes delicate in its strength because of miniaturization, and the substrate is highly likely to be affected by the pressing force of the pencil-type cleaning member 26 against the substrate W.
The aforementioned matter holds true for other substrate processing apparatuses used for processing substrates, such as a spin drying apparatus (SRD) and an IPA (isopropyl alcohol) drying apparatus which are used as semiconductor wafer processing apparatuses.
The applicant of the present invention has proposed a substrate gripping apparatus capable of rotating at a high speed by minimizing a weight of a rotating unit, and a substrate cleaning apparatus configured to prevent a cleaned substrate from being re-contaminated in a drying step as disclosed in Japanese laid-open patent publication No. 10-59540 and Japanese laid-open patent publication No. 2004-356517. There has been proposed a cleaning apparatus using a mechanism, as a holding member for holding a peripheral portion of a substrate, which has a contact member configured to be brought into contact with the peripheral portion of the substrate, a stepped portion configured to support a peripheral portion of a lower surface of the substrate, and protrusion-like retaining portions for retaining an upper surface of the substrate as disclosed in Japanese laid-open patent publication No. 8-255776. Further, there has been proposed a substrate holding apparatus which has a relatively long inclined surface inclined downward and spreading out wide toward its end, and a body having a tapered portion positioned below the inclined surface and formed by a gently inclined stepped portion as disclosed in Japanese laid-open patent publication No. 2003-303871. Furthermore, there has been proposed a substrate processing apparatus in which the substrate is rotated while supporting the entire circumference of the substrate as disclosed in Japanese patent No. 3512322.
However, the above conventional technology is not the one in which the substrate is accepted reliably within an opening (scoop opening) constituted by guide surfaces of guide portions while limiting heights of the guide portions as law as possible, the inner circumferential surfaces of the guide portions serving as guide surfaces for guiding the outer circumferential end surface of the substrate and positioning the substrate.